Carbon fibre reinforced plastic members, with their outstanding characteristics of light weight, high strength and high modulus, are widely used for sporting goods and industrial structural materials.
By using carbon fibre reinforced plastics it is possible to reduce the weight of members thereof in comparison to conventional materials, but carbon fibre reinforced plastics can exhibit a dangerous form of failure differing from that of conventional materials such as metals and, because of this, applications are either restricted or it may not be possible to fully manifest the outstanding characteristics of these materials in their applications.
For example, reducing the weight of ski-poles is of considerable significance but it is necessary that, should they break during use, the fracture surface presents no danger to the body. When conventional aluminium alloy ski-poles undergo failure, they mostly merely fold-over without breaking apart, but carbon fibre reinforced ski-poles which have become increasing popular in recent years comparatively frequently break apart when undergoing failure.
Furthermore, racing bicycle frames are another application where there is a strong demand for a reduction in weight and carbon fibre reinforced plastics are being used for this purpose. However, it is dangerous if, when the frame undergoes failure in an accident, it breaks apart and so it is desirable that even when undergoing failure that it does not break apart but remains intact.
Again, carbon fibre reinforced plastics are often used in order to reduce the weight of golf club shafts, but when the ground or a tree, etc, is struck as a result of a miss-shot, the situation may arise where the shaft snaps and the club head is sent flying. This is likely to be a particular problem when used by technically inexperienced children, and it is desirable that even when undergoing failure that it does not break apart but remains intact.
There are also many other applications such as wheel-chairs and badminton racquet shafts where a reduction in weight is desired and where it is also desired that those members with a strong possibility of coming into contact with the human body do not split apart should failure occur.
To deal with this problem in the case of ski-poles for example, a combination of glass fibre fabric or metal fibres with the carbon fibre reinforced plastic has been employed. However, such methods require the use of quite a large amount of glass fibre or metal fibre, so that the weight of the ski-pole increases or its rigidity is lowered and it becomes more difficult to use. Additionally, as well as high performance metal fibres being generally expensive, fabrication processability is poor and there is usually an increase in the cost of the ski-pole.
Again, in the case of bicycle frames and handle bars too, as described in Japanese Unexamined Patent Publication Nos 5-69874 and 5-147569, the method of incorporating, as reinforcing fibre, metal fibre and some fibre other than metal fibre for preventing breaking apart is also known. However, in such cases the problem also frequently arises or increased weight or raised cost.
The objective of the present invention lies in resolving the aforesaid problem of the prior-art and offering, comparatively cheaply, fibre reinforced plastic members which, while retaining the outstanding characteristics of carbon fibre reinforced plastics of light weight and high strength, do not readily break apart at the time of failure or exhibit a dangerous failure mode, and so may be used safely as ski poles, bicycle frames, golf club shafts and the like.